sympy/sympy — pull request #1814 by Manoj-Kumar-S (2013-02-21 20:07:57+00:00)
Title: Direct Derivatives Implementation.

This deals with the direct solving of differential equations of the form d(g(x) * F(x)) = 0 .
As shown in issue http://code.google.com/p/sympy/issues/detail?id=3160 .

I have added a new hint called 'direct' which directly integrates the function of the above mentioned form, without calling odesimp.

from sympy import *
from sympy.abc import x
f = Function('f')
d = Derivative(x*f(x) , x , x, x)
dsolve(d , f(x))
f(x) == C1/x + C2 + C3*x

I've also tried to make necessary changes to classify_ode , so that it returns 'direct' also.
classify_ode(d , f(x))
('direct',)

Do review the code , and tell me wherever to change it.